[The evaluation of 3DFT time-of-flight MR-angiography versus angiography in the study of carotid atheromatous lesions with a review of the literature].

In 37 patients suspected of having a stroke 71 carotid bifurcations were explored by MR-angiography and by digital angiography the reference technique. A 3D sequence was acquired with the time-of-flight technique, using a transmitter-receiver cranial coil, followed by a strictly receiver Helmoltz coil on a 1 Tesla magnet. Two examiners evaluated the carotid bifurcations and measured the degree of stenosis in terms of diameters, according to the north american symptomatic carotid endarterectomy trial (NASCET). Five classes were established: class 1: normal; class 2: 1 to 29%; class 3: 30 to 69%; class 4: 70 to 99% and class 5: thrombosis. The results obtained in the determination of classes were identical with both coils: the coefficient of correlation with straight angiography were 0.973 with the cranial coil and 0.966 with the Helmoltz coil. Five stenoses were overestimated and classified as Class 3 instead of Class 2. The five stenoses greater than 70% (Class 4) showed a signal-void area at their level, due to severe dephasing induced by turbulences. Finally, there was a false-negative image of occlusion: the high-intensity signal of the thrombus was mistaken for one of flow. The data of our study were in accordance with the excellent results obtained by several authors in the literature, which makes it possible for us to propose this type of examination as a novel mean of investigating bifurcations of carotid arteries. Provided a strict technique is applied, and in addition to carotid bifurcation the Willis' circle and the cerebral parenchyma are explored, MR-angiography can complete the results of Doppler-echo. Standard arteriography could then be reserved to surgical patients and to those with discordant results of MR-arteriography and Doppler echo systems.